A6Q2

#install.packages("rstatix")
library(readxl)
library(ggpubr)

## Loading required package: ggplot2

library(effectsize)
library(rstatix)

## 
## Attaching package: 'rstatix'

## The following objects are masked from 'package:effectsize':
## 
##     cohens_d, eta_squared

## The following object is masked from 'package:stats':
## 
##     filter

DatasetZ <- read_excel("C:/Users/supri/Downloads/A6Q2.xlsx")
Before <- DatasetZ$After
After <- DatasetZ$Before

Differences <- After - Before

mean(Before, na.rm = TRUE)

## [1] 57.17874

median(Before, na.rm = TRUE)

## [1] 58.36459

sd(Before, na.rm = TRUE)

## [1] 14.39364

mean(After, na.rm = TRUE)

## [1] 76.13299

median(After, na.rm = TRUE)

## [1] 75.95988

sd(After, na.rm = TRUE)

## [1] 7.781323

hist(Differences,
     main = "Histogram of Difference Scores",
     xlab = "Value",
     ylab = "Frequency",
     col = "blue",
     border = "black",
     breaks = 20)

#Histogram of Difference Scores
#The difference scores look [abnormally] distributed.
#The data is [negatively skewed].
#The data [does not have] a proper bell curve.
boxplot(Differences,
        main = "Distribution of Score Differences (After - Before)",
        ylab = "Difference in Scores",
        col = "blue",
        border = "darkblue")

#Boxplot
#There is dots outside the boxplot.
#The dots [are not] close to the whiskers.
#The dots [are] very far away from the whiskers.
#Based on these findings, the boxplot is [normal]

shapiro.test(Differences)

## 
##  Shapiro-Wilk normality test
## 
## data:  Differences
## W = 0.89142, p-value = 0.02856

#Shapiro-Wilk Difference Scores
#The data is normally distributed, (p = .029).
wilcox.test(Before, After, paired = TRUE, na.action = na.omit)

## 
##  Wilcoxon signed rank exact test
## 
## data:  Before and After
## V = 0, p-value = 1.907e-06
## alternative hypothesis: true location shift is not equal to 0

df_long <- data.frame(
  id = rep(1:length(Before), 2),
  time = rep(c("Before", "After"), each = length(Before)),
  score = c(Before, After)
)

wilcox_effsize(df_long, score ~ time, paired = TRUE)

## # A tibble: 1 × 7
##   .y.   group1 group2 effsize    n1    n2 magnitude
## * <chr> <chr>  <chr>    <dbl> <int> <int> <ord>    
## 1 score After  Before   0.877    20    20 large

#A Wilcoxon Signed-Rank Test was conducted to determine if there was a difference in Body Weight before Keto diet versus after Keto diet.
#Before scores (Mdn = 75.96) were significantly  different from after scores (Mdn = 58.36), V = 210, p < .001 .
#The effect size was very large, r = .88.